Alloy



. ?atenteol Jan. 20, 106 3 3,075,340 ALLDY Alired L. Donlevy, San Leandro, and Jack K. Y. Hunt,

Berkeley, Qaiih, assignors to dtaufier Unethical finnpany, New York, NFL, a corporation of Delaware No Brewing. Filed Apr. 53, 1961, $81. No. 102,637 6 Claims. (til. 75-174)- The present invention is concerned wtih a novel alloy of tantalum. More specifically, the alloy of the present invention contains tantalum, tungsten, molybdenum, and zirconium.

Alloys of tantalum metal are commercially important because of their great strength at elevated temperatures. The particular alloy of tantalum with which the present application is concerned likewise exhibits excellent strength characteristics. However, the alloy herein disclosed possesses much greater ease of fabricability with respect to tantalum alloys of the prior art. This greater ease of fabricability is particularly evident when rolling such tanta um alloys into sheets.

For example, the comparable tantalum alloy of the prior art which exhibits equivalent strength requires temperatures of approximately 1800 F. in order to roll the alloy into sheets. On the other hand, the alloy of the present invention may be rolled into sheets at temperatures of 600 F. or even lower.

As previously stated, the alloy of the present invention contains, in addition to the element tantalum, the elements tungsten, molybdenum, and zirconium. Tungsten is pres ent in the amount of from 9 to l3% by weight. Moylbdenum is present in the amount of from 1 to 3% by weight and zirconium makes up from 0.5 to 1.5% by weight. The remainder of the alloy is entirely tantalum. However, the alloy may also contain up to 0.3% boron. Within these ranges, alloys are made having high strength at elevated temperatures and outstanding ease of fabrication.

Optimum results have been obtained when the alloy consists of 10% tungsten, 2% molybdenum, and 1% zirconium with the remainder tantalum-ell percentages being weight percentages. The fabricability of the alloy or" the present invention can be improved still further by incorporating in them small amounts of boron. The amount of boron incorporated may vary between 0.01 and 0.3% on a weight basis. The preferred amount of boron to be added is from 0.08 to 0.2% and this should be distributed uniformly throughout the alloy. The optimum weight percentage of the added boron is around 0.1%.

The word fabricating as used in the present applica tion refers to the operation whereby pressure is used to change the shape of the object. It includes such operations as forging, extruding, hammering and particularly rolling.

The following example is given solely for the purpose of illustration and is not to be considered a limitation on the present invention.

Example 1 Finely divided metals were mixed in the following proport ons by weight: 87% tantalum, 10% tungsten, 2% molybdenum, and 1% zirconium. For ease of handling the mixture was compressed into the form of a bar. The bar was then melted in an electron beam furnace operating at a vacuum below 0.1 micron. The mixture was then allowed to solidify into an ingot which was forged not substantially alter the into a plate. The resulting plate was then conditioned, i.e., it was machined to remove the oxide film and then stress relieved. The conditioned plate was then rolled in a two high mill at a temperature of 600 F. A sheet of the alloy which was 60 mils thick resulted and as rolled had a tensile strength of 184,000 psi. The sheet was then stress relieved by heating in a vacuum for one hour at 3000 F. After this operation the sheet had the following properties-tensile strength at room temperature was 101,000 p.s.i.; tensile strength at 3600 F. was 13,000 psi. The modulus of elasticity at 3600 F. was 10.0 x 10 psi.

At this point, it should be noted that never before has a tantalum alloy of comparable strength been rolled at a temperature as low as 600 F. In addition to the obviously greater ease of handling, greater economy of ma terials is obtained by being able to roll or iabricate at the much lower temperature. It should also be emphasized that rolling at this lower temperature also results in much etter surface characteristics.

Example 2 The procedure of Example 1 supra was herein followed, except that 0.1% by weight of finely divided boron was added to the initial mixture of metals and evenly distributed therethrough. The resulting sheet had physical properties substantially the same as those described above exce t that the fabricability was even more greatly improved and the crystal size was reduced.

Other alloys within ranges previously mentioned with and without boron in amounts varying from 0.01% to 0.3% were formulated with similar results being obtained.

Many variations will occur to those skilled in the art without departing from the intent or scope of the present invention and such variations are to be considered a part of the present invention. For example, the weight percentage of tantalum given in the previous examples could be altered by adding another metal or metals which would properties of the alloy of the present invention. Columbium would be an example, since when added in minor amounts to the alloy of the present invention, the properties of the alloy would be substantially unchanged.

We claim:

1. An alloy consisting essentially of, on a weight basis, from 9 to 13% tungsten, from 1 to 3% molybdenum, from 0.5 to 1.5% zirconium, and the balance being tantalum.

2. An alloy consisting essentially of, on a weight basis, 913% tungsten, 13% molybdenum, LS-1.5% zirconium, (ml-0.3% boron and the balance being tantalum.

3. An alloy consisting essentially of, on a weight basis, 10% tungsten, 2% molybdenum, 1% zirconium and 87% tantalum.

4. An alloy consisting essentially of, on a weight basis, 10% tungsten, 2% molybdenum, 1% zirconium, 0.08- 0.2% boron, and the balance being tantalum.

5. A tantalum alloy having good strength at high temperatures and good fabrication properties, said alloy consisting of tungsten in amounts ranging from 9 to 13%, molybdenum in amounts ranging from 1 to 3%, zirconium in amounts ranging from 0.5 to 1.5% and the balance tantalum.

6. A tantalum alloy having a fine grain structure, good strength at high temperatures and good fabrication properties, said alloy consisting of tungstan in amounts rang- FOREIGN PATENTS ing from 9 to 13%, molybdenum in amounts ranging 291,297 Austria 7 5 from i to 3%, zirconium in amounts ranging from 0.5 to 1 193 191 France Aug 24 1955 1.5%, borsn in amounts ranging from 9.01 to 0.3%, and 1,222,977 France Jan. 25, 1969 the 0' 1 '10? tamalu n OTHER REFERENCES Refeyences Cited in the fil f this Patent Schmidt et aL: Mechanical Properties of T antaium- B A1 A.S. UNITED STATES PATENTS sgg isllfifays, M Transacuons, v01 53, 1961, pages 1,167,827 Kaiser Ian 11, 1916 10 

1. AN ALLOY CONSISTING ESSENTIALLY OF, ON A WEIGHT BASIS, FROM 9 TO 13% TUNGSTEN, FROM 1 TO 3% MOLYBDENUM, FROM 0.5 TO 1.5% ZIRCONIUM, AND THE BALANCE BEING TANTALUM.
 2. AN ALLOY CONSISTING ESSENTIALLY OF, ON A WEIGHT BASIS, 9-13% TUBGSTEN, 1-3% MOLYBDENUM, 0.5-1.5% ZIRCONIUM, 0.01-0.3% BORON AND THE BALANCE BEING TANTALUM. 